Locomotive boiler



4 1927. May 2 M. MAHONEY LOCOMOTIVE BOILER Filed Jan. 15. 1925 S Sheets-Sheet l Filed Jan. 15. 1925 s Sheets-Sheet 2 5 M W J m 3 m k Z M a 5 e y M. MAHONEY LOCOMOTIVE BOILER Filed Jan. 15. 1925 3 Sheets-Sheet 3 I M/es/ il I. i wa lumm lnnuw w M mmmmwmmmmm wm mmmm mmwwm wm mmmmm mmm E i; 1%; K

Patented May 24, 1927.

MYLES MAHONEY; F -MONTREAL, QUEBEC, CANADA.

LOCOMOTIVE BOILER.

Application filed January The principal object of the present invention is to provide a boiler which will in the main conform to present day standards but which will have a higher efficiency.

The salient features of the invention are:

(a) The construction and arrangement of parts obtaining a horizontal division of the fire tubes for the purpose of causing the dcflection of a part of the fire gases through tubes in the evaporator above'the tire box, and thereby increasing the evaporating surface and at the same time providing a safety element.

(6) Augmenting the circulatory action of the water through the boiler.

More specifically-stated the invention consists of a division of the fire tubes by the crown sheet cuttingotf the top group andconnecting this top group to the top corner of the fire-box at the back of the latter and to the smoke box at the front-of the boiler barrel. These'pipes of the top group are of particular configuration in that each 15 formed With an upwardly projecting bend,-

thus causing the fire gases to impinge against the interior of these pipes in the vicinity of the bend. the effect being that this portion of each pipe is of much higher ten'uaeraturo than the remainderot the pipes in the group. This structure, therefore, presents I a safety Z0110 because in the event of the level of the water in the ovap n'ator sinking below what is considered a safe level the first point. exposed is the bends in these pipes, and as these bends have a vcryhigh; temperature they will rapidly burn-'ont with the result that water or steam will be immediately projected into the portion of the fire-box contiguous to the door and an alarm be given to the "en gine crew. If the leak is not noticed the upwardly extending bend inclining downwardly the portions of the pipes from the bend to the fire-box establishes a tlow of steam and water from the boiler to firebox thus putting out the fire before any damage results. Another feature of the invention consists in the augmenting of the circulation of the water through the evaporator. The arch tubes are connected at their forward ends to the top of the front water leg of the tirebox and their rear ends are connected to the upper end of the rear water leg of the lire-box in the vicinity of the'top rear corner of the fire-box. These arch tubes are made of slightly increasing diameter from their lower to their upper .ends. The upper rear rear-leg of the boiler.

15, 1925. Serial No. 2,581.

\ the evaporator at this point is reduced below the capacity of the adjacent portion of the The effect is that a siphoning action is produced because of the gradual increase of capacity ot the arch tubes, the upper portion of the rear leg of the boiler, the portion of the evaporator atovethe chamber and the portion of the evaporator immediately following. I have discovered that this gradual increasing of capacity of the water conductor has the ef fect of augmenting the circulation.

For full comprehension, however, of my invention reference must :be had to the ac companying drawings in which similar refcrence characters indicate the same parts and wherein Figure l is a diagran'unatic longitudinal sectional-view of a locomotive boiler constructed according to my invention;

Figure 2 is a transverse vertical sectional view takenon line 22 Figure 1;

Figure 3 is asimilar: view taken on line 3-3 Figure 1 Figure 4 is a sectional View taken on line 1-4. Figure 1 showing the front tube sheet;

Figure 5 is a similar View to Figure i of the tire-box end of the boiler; and

Figure 6 is a fragmentary diagrammatic longitudinal sectional view of the crown sheet and associated parts illustrating a different location of the upward bends in the safety tubes.

Figure 7 is a sectional view taken through one of the crown sheet tubes at the point l in Figure 1, and'i'llustnu Eng 10 1 lat for supporting the tubes upon the crown sheet LOCOHIOtlYQ boilers are constructed in many diflcrent sizes but the same general construction and arrangement of the paadopted as standard in all sizes althougl minor changes such as in the number at tubesemployed; combustion chamber, etc. must of necessity be made to secure the desired efficiency for each size and I have therefore shown my invention embodied in a locomotive boiler of a size which will e11- able a clear and complete explanation of all of the features of my invention.

It is to be distinctly understood however ltlii that I do not confine the invention to this size as minor alterations may be ma .e to suit requirements of different sizes without departing from the spirit of the invention.

Referring to the accompanying drawings the boiler barrel is indicated at 2, the tirebox at 3, the hack tube sheet at l, the front tube sheet at 4, the fire tubes at Ii, the superheater fines at 5 into which the superheater units are inserted. the crown sheet at 6, the siphon arch tubes at 7, the arch brick supported thereon at 8, and the side and rear or back walls or sheets of the firebox at 9 and 10 respectively. The smoke box is indicated at 4A.

The reference character 12 indicates the location of the crown sheet in locomotives of this particular size in standard locomotive practice of to-day while 13 indicates the normal worhing water level. It must be borne in mind that a water level must always be maintained to a sutlicient depth to cover the crown sheet irrespective of any grade on which the locomotive may travel, otherwise that portion of the crown sheet which at any time in service becomes uncovered will be burned through causing serious loss of life and great damage.

Gauges are provided for indicating the water level but while evaporation is progres'sing the water may be allowed to become so low as to uncover the crown sheet, due to carelessness of the enginemen, who through neglect of proper attention tail to keep the water at a safe level. corroded or defective gauge cocks and water gauge glasses may indicate water levels which do not exist inside the boiler and other causes such as bad feed water, often render the indications of water level to be safe when the level is actually at a dangerous depth. To overcome these dangerous uncertainties I provide a downward otl'set l t in the crown sheet, preferably adjacent to the rear of firebox which makes it possible to extend one or more rows of fire tubes rearwardly over the crown sheet as indicated at 5 the rear ends of these extended crown sheet tubes having their ends mounted in the auxiliary tube sheet LP constituted by the vertically disposed portion of the offset. In locomotive boilers of the smaller sizes it may be desirable to extend only one row of the tubes over the crown sheet as is illustrated, whereas in the larger sizes it might be desirable to extend one or more of the topmost rows. These extended tubes are sloped substantially in parallelism with the crown sheet towards the rear end of the firebox to locate their highest point preferably above the lirebox This construction and arrangement of parts is most advantageous. In the first place danger of the crown sheet burning is practically eliminated because the tubes must burn first, and the burning of the tubes would at once warn the engine men of the dangerous water level. Secondly, a greater heating surface is provided, the loss in tirebox heating surface engendered by the lowering of the crown sheet being more than offset by the increased surface provided by the extended tubes. This is clearly shown from the following comparison which is based on Coles System recognized as the standard basis of measurement for computing locomotive boiler evaporation and compares a standard locomotive boiler with the same boiler constructed according to my invention M y improved boiler.

lie-5% O. D. tubes- H 3 4 O. D. rubes-l911 he Mi e 4" O. D. crown tubes--7 4-3 0. D. tubesarch tubes U I izristing boiler.

O. D. arch tubes 9*3 long.

3516 sq. It. total.

My improved boiler total lbs. steam per honr.

2378 sq. ft. heating surlaeex 3.35:

ft. healing surfaceX 8. 55 19413 lbs. It. heating su1faoe 10..l3 8519 lbs. ft. heating surfaeeXlL= 2093 lbs. It. heating SurfaceXBOflO 2l60 lbs.

. ft. heating surfaceb "m 'lotal 4593.;lhs. Steam per hr.

19856 lbs. 89675 sq. gt. seating surfacexmfi 9176 lbs. 2 sq. t. caring surface 215 sq. ft. firebox H. l

Total 42287 lbs.

Steam per hr. 35

base boiler diameter and cause considerable increase in weight. This increased evaporation capacity may vary according to the size of the boiler from 3% to 8%. Another ad vantage obtained with this arrangement is that the increased heating surface is applied to that portion of the boiler where it will createfthe greatest circulation because the legs only have to provide a vertical cirthe tubes are located in close proximity to thecrownsheet causinga rapid evaporation of tliev'atei' therebetween.

The offset 14; in the crown sheet may be located at any "desired point but that location which I find preferable is adjacent the back of the firebox, where it forms an upwardly extending chamber'in full open communication with the tircl'iox. \Vhen so lo cated the hot flame gases in the firebox are caused to impinge against the firebox back as indicated by the arrows in Figure 5 thereby increasing the value of the firebox heating surface and causing a better circulation in the back water leg 15 whichin thestandard types is inclined to be sluggish.

Notwithstanding the fact that the lowering of the crown sheet reduces the firebox cubical volume a gas flow is obtained in the present construction which results in a more complete combustion than would be obtained in a firebox having its crown sheet located at the standard level. This is due to the fact that the extra exits provided by the crown sheet tubes create a more uniform distribution of the draft over the fuel bed than would be the case in standard locomotive fireboxes, the pull of the draft from the crown tubes causing the gas flow to break away from its stream line formation over the brick arch. As a result the gases of greatest temperature and therefore the lightest and of highest velocity rise to the highest part of the firebox behind the brick arch and enter the crown sheet tubes at approximately 700 Fahrenheit hotter than their temperature would be at the firebox tube sheet if they passed through the tubes mounted in such sheet. The unconsumed particles of fuel and the heavier gases pass over the brick arch of the firebox into the combustion chamber 3 which then has a relatively larger volume than would be the case without the crown sheet tubes, owing to the fact that through the latter a large volume of gases is taken away which would otherwise have to pass through the combustion chamber. This separating action of the gases which takes place behind the brick arch opening causes a better mixing of the products of combustion and loss due to the formation of carbon monoxide gases and other incomplete combustion is reduced to a minimum. In addition the firebox back sheet 10 has a much more effective gas flow along its surface than the case in locomotive fireboxes now in use and a vigorous circulation of the water behind the back sheet and in the legs at the sides of the the box, where the circulation is usually slug gish, takes place. Circulation tests in existing firebo'xes show very little horizontal flow in the firebox legs 'owing to the fact that culation to replace the water evaporated over the crownsheet." By converting the firebox back sheetinto a' more active l121tlflg'SUI- face a greatly increased horizontal flow is obtained as largeramounts of water are evaporated at the rear of the firebox and must be replaced. The crown sheet"tubes lation because the temperature centerof gravity 18 located further towards the rear will further ihcrease the side sheet circuof the firebox, thus inducing water flow" further along the firebox legs.

Another feature of my'invention IS the provision of means for causing'a vigorous circulation of the comparatively cool water at the bottom of the boiler barrel. This means consists of the arch tubes 7 which are gradually increased in diameter from their lower ends'upwardly so that a siphon action is obtainedwhich draws the water from the bottom of the boiler barrel and discharges it into the water space at the upper rear part of the firebox. This flow induces a circulation up the back firebox water leg 15 and the rear portions of the side legs 16 and 17. The effect of this upward "chambered extension of the firebox and the gradual upward expansion 'of the arch tubes is that gradually increasing capacity is presented from the smallends of the arch tubes where they are connected to the upper end of the forward water leg of the tireb'ox'and this increasingcapacity continuesthroiigh the arch tubes and through the upper portion of the back water leg and through the portion of the evaporator restricted by the chamber, to the main body of the evaporator. A distinct siphoning action is produced by this increase of capacity and the circulation is augmented to a considerable degree.

The large volume of water discharged from the siphon arch tubes is thrown over the top of the crown'sheet and crown sheet tubes in its circuit of circulation towards the front of the boiler so that the added l'lcating surface of. the crown sheet tubcs'are pro-' vided with a primary flow and volume of water to add to their effectiveness.

The velocity and volume of the water discharged through siphon tubes can be theoretically calculated as follows:'

Area'at upper end of tubes 5.375 I. D.:1575 s a.

ilk)

iii)

Discharge at 15 ftfpei" sec.:2.2625 cub. ft. per sec. For 5 siphon arch tubes the discharge is then 20362 cub. ft. per hr. each of steam and water (column gives greatest discharge of half water and half steam).

The manner in which the various parts are secured together is not entered into in detail because the usual practice of locomotive boiler construction is followed. The crown sheet however is preferably constructed in two parts 6 and 6 welded or riveted together as at 6 and the latter is pref erably a half inch in thickness so that even if this plate becomes uncovered before the tubes extending above the crown sheet burn through, the tubes will still burn through or collapse before the plate becomes heat-ed enough to rupture. The plate 6 should be transversely arched concentrically to the crown sheet 6. The connection of the arch tubes to the back firebox sheet may be ef fected by flanging the firebox back sheet and welding the ends of the tubes thereto.

Means is provided for locating the fire tubes which extend over the crown sheet at a definite distance therefrom and for supporting the tubes and preventing their collapse in the event of burning. This means comprises brackets each consisting of two parts and 31 loosely connected by a pin 32, one part 30 being forked and embracing and reinforcing the tube it supports, and the other part 31 being secured to the crown sheet or back tube sheet. That portion of each of the bracket parts 30 which embraces the tube is welded thereto and extends upwardly around the same above the horizontal diametrical plane of the tube so that burning of the tube, when it occurs, is localizcd at a and collapse of the tube prevented. The loose connection between the bracket parts permits relative expansion and contraction between the tubes and firebox. The upward bends B in the tubes also permit expansion and contraction of the latter. Figure 6 shows a diflerent location in the upward bends in the tubes. the bends being located nearer the rear ends of the tubes so that the burning points B are nearer the lame gases which enter the tubes. This ensures a rapid burning of the tubes when they become uncovered. The tubes are reinforced adjacent their highest points by reinforcing members which embrace the tubes in a similar manner to the bracket members 30 shown in Figure l and prevent the collapse of the tubes in the event of burning. As alternative means of supporting the tubes, nuts adapted to form seats for tubes may be mounted upon the crown sheet radial stays. or fixed struts may be mounted upon the crown sheet.

To facilitate the removal of sediment from the crown sheet washout plugs are provided as usual in the outside wrapper sheet in line with the crown sheet top surface so that such surface may be conveniently washed off.

It will be seen from the foregoing description that a safety boiler is provided in so far as the collapse of the crown sheet due to burning occasioned by low water, is concerned, because it is impossible toburn the crown sheet without burning the safety tubes first.

Accepted practice in fire tube lengths is a ratio of sectional area of tube outside diameter to its length in inches of between and 73 to 1. The ratio of the safety tubes extending over the crown sheet in the illustrated embodiment is 40 to 1. It will seem there fore that this ratio is well within the accepted practice.

It is obvious that the nearer the upward bend in the crown sheet tubes is located to the rear end of such tubes the more rapid the burning or collapse of the same when uncovered, and it is to be distinctly understood that the location of the bend may be varied to meet requirements without departing from the scope of the present invention.

hat I claim is as follows:

1. In a locomotive boiler the combination of a boiler barrel; a smoke-box; a firebox the crown sheet whereof has an upwardly extending chamber at the top rear corner thereof and in open communication with the fire-box; fire tubes communicating with the lire-box and extending through the barrel to the smoke-box, and safety fire tubes commu nicating with the chamber and extending through the barrel above the fire-box for the purpose of directing a portion of the burning gases therethrougl'i from the top of the rear end of the fire-box to the smoke-box, each of such safety fire tubes having an upwardly extending bend adapted to direct steam and water into the upwardly extending chamber in the event of a break in the bend.

Q. A locomotive boiler such as claimed in claim 1 the upward bonds of the safety tubes whereof are located in the vicinity of the tube sheet.

3. A locomotive boiler; a firebox; a smoke-box: fire tubes extending rearwardly over the fire-box and communicating at one end with the tire-box and at their opposite ends with the smoke-box each of such tubes having a bend in an upward direction and extending from the bend downwardly towards the ends of the boiler, and means for supporting the tubes upon the fire-box and for reinforcing them adjacent their bends.

4. In a locomotive boiler the combination with a fire-box and the front and rear walls thereof, of an upwardly extending chamber in the crown sheet at the rear corner thereof and in full open communication With the fire-box, fire tubes leading forwardly from the front Wall of the fire-box, a row of fire tubes leading from the front Wall of the chamber and extending forwardly over the crown sheet and a series of upwardly expanded arch tubes leading from the lower to the chamber.

In testimony whereof I have signed my name.

M Y LES MAH ONE Y. 

